diff --git a/boards/sim/sim/sim/scripts/Make.defs b/boards/sim/sim/sim/scripts/Make.defs
index face3c1635f..09c6a5989de 100644
--- a/boards/sim/sim/sim/scripts/Make.defs
+++ b/boards/sim/sim/sim/scripts/Make.defs
@@ -42,10 +42,13 @@ ARCHDEFINES += -U__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION = -g
+  ARCHOPTIMIZATIONRUST = -g
 endif
 
 ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += -O2 -fno-strict-aliasing
+else
+  ARCHOPTIMIZATIONRUST += -C opt-level=0
 endif
 
 ifeq ($(CONFIG_STACK_CANARIES),y)
@@ -95,6 +98,7 @@ endif
 NM = $(CROSSDEV)nm
 OBJCOPY = $(CROSSDEV)objcopy
 OBJDUMP = $(CROSSDEV)objdump
+RUSTC = rustc --edition 2021
 
 CFLAGS := $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
    $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
@@ -102,6 +106,7 @@ CXXFLAGS := $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) \
    $(ARCHCPUFLAGSXX) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
 CPPFLAGS := $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS)
 AFLAGS := $(CFLAGS) -D__ASSEMBLY__
+RUSTFLAGS := $(ARCHOPTIMIZATIONRUST)
 
 ifeq ($(CONFIG_LIBCXX),y)
   # Why c++17?